Grinding mill



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`F. n. BRADLEY. GRINDING Ml L 2 SHEETS-SHEET 2 FILED FEB IIII Ill HHH i?Patented om. 2e, reza.

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FRANCIS DEAN BRADLEY, OF GOLDFIELD, NEVADA..

GRINDING MILL.

Application filed February 18, 1920. Serial No. 359,546.

ATo all whom t may concern Be it known that I, F nANors D. BRADLEY, acitizen of the United States, residing at Groldfield, in the county of'Esmeralda""and' State of Nevada, have invented a new and useful'Improvement in Grinding Mills, of which the following is aspecification.

This invention relates to cylindrical crushing and grinding mills usedin comminuting ores, minerals or the like, and more especially/ to acombination rod and pebble mill. It is a well established fact in thepresent methods of crushing ores with steel balls, that the mill must beof larger diameter to effect the necessary impact crushing than whenemploying steel rods, also due to more grinding surface in contact onthe rods and less voids between their surfaces; rod mills of a smallerdiameter are more efficient and consume less horse-power to operate;although asis commonly known, material is not pulverized to the degreeof ineness in rod mills as attained in pebble mills when used forextremely fine comminution or sliming. Rod mills for primary grindingare practically of the same diameter as the finer grinding tube mills.The `present invention combines the merits of the rod mill and the tubemill by accomplishing in a single apparatus two stage reduction,employing the more efficient method of impact crushing with rodsfollowed by l attrition grinding inv an additional compartment usingpebbles orfballs.

@ne of the objects of the present invention is to 'improve the resenttype of rod mill by dividingthe grinding cylinder into two or morecompartments wherein the primary coarse crushing is accomplished in thefirst compartment with steel rods and finer grinding is produced in thesecond compartment by the use of pebbles or balls.

AnotherI object of the invention is to provide means for reducing theviscosity .of the ground pulp 'as it passes through the mill.

Another object of the invention is to provide meansfor facilitating theinspection and removal of the rodsin the first crushing compartment. l

Another object of the invention is to provide a novel head or partitionmember for `separating the compartments and in conjunction therewithmeans for removing parts of the same to facilitate removal of thecrushing rods;

v Further objects will hereinafter appear.

The invention consists of the parts and the construction, combination.and arrangement of parts, as hereinafter more fully described andclaimed, having reference to the accompanying drawings, in which- F ig.1 Vis a central longitudinal vertical I vsection through one form of theapparatus.

Fig. '2 is a cross Section on line 2-2, Fig.' l, partly brokenV away. Fig. 3 is an enlarged section of the partition member taken at rightangles to-Fig. 2.

Fig. 4 is an end view of the interior of the apparatus showing thegrinding rods suspended on cross bars and part of the parl tition memberremoved.

Fig. 5 is a side elevation of a modified form of the apparatus partiallybroken away and partially in section.-

' Fig. 6 is an enlarged detail view of the valve attachment forsupplying solutions to the second compartment.

Referring to the drawings in detail, A indicates an elongatedcylindrical membery constructed along lines common to tube mills and thelike. This tubeor cylinder is divided by a` transverse partitiongenerally indicated by the numeral 2 and two separate compartmentsindicated at 3 andIl 4 are in this manner formed. The tube or cylinderis provided with heads 5 and 6y ofv any approved detail construction anddriven in practice in any suitable manner; The heads have trunnionsformed with axial bores constituting respectively the inlet and outletfor the material, the heads in practice -turning in suitable supportsnot shown. The respective trunnions are indicated at 7 and 8, thetrunion 7 being provided with a scoopfeed 9 by which the material to beground is delivered to the first compartment. The trunnion 8 isalsoihollow and serves asa discharge from the pebble containing chamber`ring 10 secured interior of the` cylindrical.`

shell A. This ring is provided with a pair of interspaced annularshoulders 11 for the reception of sectional interspaced head1/members 12and 13. Each head member consists of four sections such as shown in Fig.2, each section being so constructed that it may be removed independentofv any other section. This is accomplished in the following manner:

Formed on each section is a flange 14, the inner face of which isangularly disposed or inclined as at 15. Engageable with said flange isa lug 16 and adapted to draw said lug against the flange 14 andthe ring10 is a bolt 17. Each lug engages two aligned i sections and whenremoved does not disturb the remaining sections. There is one bolt 17and lug 16 for each pair of aligned sections and these serve thefunction lof securing the peripheral edges of the respective sections.Means have also been provided for centrally securing the sections. Thismeans, as shown at 18 and 19, consists of a pair of circular plateshaving shoulders formed thereon engageablewith wings or ribs 20 formedon the inner faces of the head sections. These ribs form two functions:first, that of receiving and supporting the central securing discs 18and 19; and secondly, that of blades or vanes whereby material iscarriedfrom the outer periphery of the heads to the center portion of the sameas will hereinafter be described. The `central discs 18 and 19 aresecured by means of a bolt and nut 20 and as they engage the inner endsof the ribs or vanes 20 on the respective head sections, it can readilybe seen that these are rigidly secured when in position.

By referring to Fig. 2 it will be seen that the head sections 12 areprovided with 10ngitudinally extending radially disposed slots orperforations 21. These are arranged at the periphery or near the outeredges of the several sections vand serve the function rof dischargeopenings for the material ground by the rods in the first compartment.Material entering the slots 21 collects in a central chamber 22, forwmedbetween the respective head sectionsl and it is discharged therefrom andinto the pebble chamber through radially arranged slots 23, formed inthe central securing disc 19, thematerial being elevated to said slotsby means of the ribs or vanes 20. vMaterial passing through the millwill therefore first enter through the trunnion 7 and when ground to apredetermined size enter the central chamber 22 through the radialperforations 21. 1t is then elevated to the center portion of saidchamber by the vanes 20 and then discharged into a pebble mill chamberthrough the centrally disposed perforations 23. The material is thensubjected to its final grinding action and is then discharged throughthe trunnion member 8,

1n any grinding apparatus as disintegration of the material proceeds,the superficial area of the material exposed to the surrounding crushingelements increases. This is a desirable feature in the primary crushingcompartment as an aid to grinding, but as the pulp vcontinues, on itscourse the increased friction between particles createsa sluggishness orstate of viscosity Which retards progress toward the discharge end ofthe mill. This objection is overcome in the present instance as means isprovided for introducing a solution to increase the moisturecontent andthe mobility of the semifluid mass through the final grindingcompartment.

1n Fig. 6 the detail construction of a valve for admitting the liquid isshown. The valve consists of a collar l25 which is secured to androtates in unison with the trunnion delivers 'the liquid to the annulargroove 26 and it is discharged therefrom by means of pipes 30 which aresecured to the collar 25 and rotate in unison therewith. These pipes areextended to the pebble compartment as Ashown in Fig. 1, or asillustrated in Fig. 5,

and practically any quantity of liquid may therefore be delivered bymerely regulating the flow through the pipe 29 by means of the valve 31.

One of the features of vthe present invention is the provision of ymeansfor facilitating the examination and Withdrawal of the rods. Byreferring to Fig. 5, it will be seen that a pair of port holes 16 areprovided in one side of the shell and like pair of aligned port holesare provided in the op- 4osite side of the shell. The aligned port olesare adapted to receive the rods 35 as shown in F lig./1. A manhole 17 isalso provided as shown in Figs. 1 and 5. Thejport holes are normallyclosed by plugs and similarly the manhole with a cover when the mill isoperating. In Fig. 1 a similar arrangement has been provided, i. e.,port holes 16 and a manhole 19, said manhole being formed in a headmember 6 and normally closed. U

When it is necessary to remove' the rods,

the feed to the mill is shut off, rotation stopped and the millpermitted to stand idle and assume the position shown in Fig. 1, Thecovers or plugs for the port holes16 are then removed and the cross barsinserted, during which time the mill is allowed to drain away the excesspulp through 'the trunnion outlet v8.' The mill is then turned 85 7.Formed in the outerface of this collar lis one-half a revolution, whichleaves the rods in the position shown in Figs. 4 and 5. The manholecover is neXt removed and an operator may then enter and remove thesec-l tional plates of the head members l2 and 13. This exposes the endsof the rods and those partly worn are withdrawn and passed through themanhole. New rods are similarly inserted and the whol'e operation ofinspection Vand repair is completed in a comparatively short timeinterval; The head sections l2 and 13 are replaced and similarly themanhole cover. The -mill is again rotated a one-half revolution and thecross bars 35 removed. The port holes are then closed and the mill isagain ready for operation.

While the valve 26 and certain features of the mill are more Yor lessspecific in construction, I wish it understood that variations in designand proportion may be resorted to within the scope of the appendedclaims, similarly that the materials and finish of the several partsemployed may be such as the experience and judgment of the manufacturermay dictate or varying conditions may demand.

Having thus described my invention, what l claim and desire to secure byLetters Patent is 1 In a grinding mill of the character described, apartition member dividmg the mill into two separate grinding chambers,said partition member consisting of a ring, a head member secured oneach side thereof, each head member consisting of a plurality of alignedindependent sections, means carried by the ring for securing each pairof aligned sections,A and centrally disposed means for securing the headsections, said sections of one head member having a plurality ofcircumferentially arranged openings formed in the sides thereof, andsaid securing means havinga plurality of centrally disposed openingsformed therein.

2. ln a grinding mill of the character described. a partition memberdividing the mill into two separate grinding chambers, said partitionmember consisting of a ring, a head member secured on each side thereof,cach head member consisting of a plurality of aligned independentsections, means carried by the ring for securing each pair of alignedsections, and centrally disposed means for securing the head sections,said head sections of one head member having a plurality ofcircumferentially arranged openings formed in the sides thereof, saidsecuring means having a plurality of centrally disposed openings formedtherein, and

aligned vanes formed on the respective sec-.

tions of the head members for conveying material from one set ofopenings to the other.

3. In a grinding mill the combination of a rotatable hollow drum of theclass described,

having rod means for grinding materiai and provided with means forlsuspending the rods as a whole within the drum, said means comprising apair of removable, transversely positioned rods in the drum, said rodsbeing positioned one near 'each end of the drum.

4. In a grinding mill of the character described, a partition memberdividing the mill into two aligned compartments and an intermediatecompartment, said partition member consisting .of a ring secured withinthe casing and an annular seat formed on each side of the ring, a headmember adapted to bei secured with relation to each seat, one headmemberhaving a plurality Aof circum 80 ferentially arranged radial openingsformed in the side thereof and ysaid opposite head member having aplurality of centrally disposed radial openings formed therein.

5. ln a grinding mill of the character de- 35 scribed, a partitionmember dividing the" mill into two aligned compartments and anintermediate compartment, saidl partitioln member consisting of a ringsecured within the casing and an annular seat formed on 9o each sidel ofthe ring, a head member adapted to be secured with relation toeach seat,one head member having a'plurality of circumferentiall arranged openingsformednear the perip ery thereof and said opposite head member having aplurality of centrally disposed openings, and vanes formed between thehead members for'conveying material entering through the peripherallyarranged openings to the centrally disposed openings. 10@

6. In a grinding mill the combination of a rotatable hollow drum of theclass described, having rod means for grinding material and providedwith means for suspending the rods as a whole within the drum for thepur.- pose of removing the rods in an inoperative position, said meanscomprising removable transversely positioned supports in the drum.

7. ln a grinding mill, the combination of 11@ a rotatable hollow drum ofthe class described having rod members for grinding material, asectional` removable partition member dividing the mill into twoseparate .grinding chambers, substantially as described, and meansprovided for supporting the rods in an inoperative position to permitremoval of the rods through the sectional partition member.

8. In a grindingmill of the character described a revolvable drum, apartition member within the drum forming a pair of sepa-- rated grindingcompartments, grinding means in each compartment, means for feedingmaterial to be ground to one compartment, means for transferring theground material through the partitionrmember to the second grindingcompartment, means permitting discharge of the further ground materialfrom said compartment, and means 13o for maintaininguniform viscosity ofthet material t0 be ground during its discharge through the successivecompartments, said lthe material will be gradually reduced as it pas-sesthrough the compartments, and means for delivering water in regulatedquantities to one of said compartments 15 whereby the material will flowthrough both the compartments with Substantially equal mobility.

' In testimony whereofI have hereunto set my hand in the presence of twosubscribing 20 witnesses.

FRANCIS DEAN BRADLEY.

Witnesses: y f

En LEMBCKE, C. W. MARLATT.

